Glandless electrically driven pumps



1969 v. IVANOFF GLANDLESS ELECTRICALLY DRIVEN PUMPS Filed June 21, 1966R F NF E0 u mw I m T m V ATTORNEY United States Patent 3,421,445GLANDLESS ELECTRICALLY DRIVEN PUMPS Victor Ivanolf, Harpenden, England,assignor to Hayward Tyler & Company Limited Filed June 21, 1966, Ser.No. 559,261 Claims priority, application Great Britain, June 24, 1965,

26,799/ 65 US. Cl. 10387 2 Claims Int. Cl. F0411 13/06; F04d 29/10; F04d29/02 ABSTRACT OF THE DISCLOSURE The invention relates to glandlesselectrical motor/ pump combinations in which the motor housing and pumphousing are in communication with each other through a narrow annularclearance between the shaft and a neck portion surrounding the shaft. Insuch combinations, the-re is a tendency, when the pump is at rest, forconvection currents to be established which convey hot liquid up oneside of the narrow annular clearance and cooler liquids down the otherside. This results in distortion of the pump shaft which is removed inaccordance with the invention by providing the shaft, in the neckregion, with a sleeve of thermal insulating material. This can take theform of a layer of asbestos or heat resistant plastics material, or maybe constituted by a layer of liquid within an outer retaining sleeve.

The invention relates to vertical glandless electrically driven pumps,particularly for pumping hot liquids. In such units the motor isnormally of the squirrel cage induction type constructed for operatingfilled with the pumped liquid cooled to a lower temperature. The motorhousing forms a common liquid enclosure with the pump housing, the twohousings being connected by a neck portion and the communicating spacebetween the two being the narrow annulus round the driving shaft, whereit extends through the neck portion.

In the particular case where the driving motor is positioned above thepump there is a tendency for thermal convection currents to be set upbetween the cold relatively heavy liquid in the motor and the hotrelatively light liquid in the pump. When the unit is running theseconvection currents are broken up by the peripheral drag of the rotatingshaft, but when the unit is stopped convection currents are quicklyestablished.

The hot liquid tends to rise in the annulus on one side of the shaftinto the motor and the cold current tends to descend into the pump onthe other side of the shaft. This produces unequal heating of theopposite sides of the shaft within the annulus and distorts it byasymmetrical thermal expansion. This distortion of the shaft may cause aclosing up of the fine working clearances between the rotating and thestationary components within the pump and may result in seizure onstarting up the pump again.

The purpose of the invention is to minimise this distortion of the shaftto a very small acceptable value.

In accordance with the invention (whose precise scope is defined in theappended claims) the shaft, where it passes through the neck portion, isprovided with a thin sleeve of thermal insulating material. The fittingof this sleeve does not directly affect the temperatures of theascending and descending currents, but causes the main temperature dropbetween the two sides of the shaft to Patented Jan. 14, 1969 take placein the insulation itself, thus reducing substantially the temperaturedifferences in any transverse plane within the shaft and thereby greatlyreducing the shaft distortion.

Some constructional forms of insulating means in accordance with theinvention will now be described, by way of example, with reference tothe accompanying drawings in which:

FIGURE 1 is a diagrammatic part sectional elevation of a glandless,electrically driven pump,

FIGURE 2 is a sectional elevation, on a larger scale, through the neckportion of the pump shown in FIGURE 1; and

FIGURE 3 is a view, similar to FIGURE 2 of a second embodiment of theinvention.

The electrically driven pump shown in FIGURE 1 comprises, in knownmanner, an upper, motor housing 11 connected by a narrower neck portion12 to a pump housing 13, and a driving shaft 14 which extends throughthe neck portion with annular clearance and carries the motor rotor atits upper end and the pump impeller 16 at its lower end. The narrowannular clearance between the neck portion 12 and the shaft 14 affordsliquid communication between the pump housing 13 and the motor housing11 which both normally contain some of the liquid to be pumped.

In accordance with the invention, and as best seen in FIGURE 2, theshaft 14, where it passes through the neck portion 12, is provided witha thin sleeve 21 of asbestos or other thermal insulating materialretained in a cylindrical recess in the bore of a thin outer sleeve 22of a rigid material, preferably metal which is secured to the shaft 14by being shrunk onto it or fixed by one or more screws 23.

In a modification of this embodiment, the solid insulating material isomitted and the rigid outer sleeve 22 has a hole or gap so that thecylindrical recess fills with liquid. The liquid in the recess thenforms the insulating sleeve 21, as most liquids are poor conductors ofheat unless agitated.

In the embodiment shown in FIGURE 3, the outer sleeve 22 is omitted, andthe insulating sleeve 21 is constituted by a layer of insulatingmaterial applied direct and adhering to the shaft 14. This sleeve may,for example, be constituted by a layer of ceramic material formed byspraying onto the shaft a hot ceramic powder, or by a coating of heatresistant synthetic plastics material.

I claim:

1. In a vertical, glandless electrically driven pump of the typecomprising a pump housing, a motor housing, a neck portion connectingsaid housings, and a drive shaft extending from the motor housing withannular clearance through said neck portion into the pump housing sothat said annular clearance permits the flow of liquid between saidhousings, the improvement comprising the provision of a thin sleeve ofthermal insulating material encompassing that portion of the shaft whichextends through said neck portion, and an outer rigid sleeve secured tosaid shaft for retaining said insulating sleeve in position on saidshaft portion within the neck portion.

2. The improvement claimed in claim 1, wherein said sleeve of insulatingmaterial is constituted by a layer of liquid within said outer sleeve.

(References on following page) 3 References Cited 1,925,898 9/1933 Fritz103114 3,255,702 6/1966 Gehrm 103--114 UNITED STATES PATENTS FOREIGNPATENTS 2 19 Miller 3 114 5 1,239,467 7/1960 France. 12/1939 1 b 103876/1947 gg f i HENRY F. RADUAZO, Primary Examiner. 2/1954 Guyer 1038711/1959 White 103 s7 12/1963 Moser 103-87 10 103111, 114; 308237

